Artificial knee joint



Dec. 30, 1947. R. F. MARKKULA 2,433,571

ARTIFICIAL KNEE JOINT Filed Aug. 9, 1946 INVENTOR. RAYMOND E MARKKULA b/a ATTORNEY Patented Dec. 30, 1947 UNITED STATES PATENT GFFIQE ARTIFICIAL KNEE JOINT Raymond F. Markkula, Los Angeles, Calif. Application August 9, 1946, Serial No. 689,560

'5 Claims.

My invention relates to leg braces and the principal object of the invention is the provision of a leg brace having an improved knee joint characterized by case and reliability of operation, and low cost of production.

Among the several types of leg braces there is need of one in which the knee may be bent only when parts are manually released or unlocked, the joint being still or unbendable at other times. In such a brace, the joint locking means must be completely secure, since their accidental release will inevitably cause a fall, which may result in further physical injury, and in any case, means a loss of confidence by the wearer in his brace. Such loss of confidence alone is serious. While locking must be dependably secure, the joint must be freed by uncomplicated manual manipulation; and because the device is intended to be low in cost to the user, the simplest of parts are used.

Referring to the drawings: Figure l is a side elevation of the central portion of my leg brace which includes the knee joint. The joint structure shown is duplicated in the opposite side of the brace as shown in Figure 2. Portions are cut away to disclose the construction. Figure 2 is a rear elevation of the joint portion of the brace, taken in a plane at right angles to'the plane of Figure 1. Figure 3 is a side elevation on a reduced scale of the entire leg brace, but without the complete straps for holding it on the leg. Figure 4 is a plan view of the latch yoke. The direction in which the view is taken is indicated by the arrow 3 in Figure 1. Figure 5 is a sectional view thru the leg brace showing the bows for connecting the twin sides. The plane of section is indicated by the line 55 of Figure 3.

While my knee joint lock may be used on but one side of the brace, there being only a plain pivot joint in the opposite side, it is preferred to make a generally lighter structure and place one on each side of the brace, connecting and coordinating the latch or lock mechanisms so that the two are operated together. Since the mechanisms are substantially identical, but one will be described in detail.

My leg brace comprises an upper side plate 2, and lower side plate 3, each of fiat rectangular cross section. The upper plates are connected by two bows 4 and 5, and the lower plates by a bow 6. These bows fit around the rear side of the braced leg, forming with the side plates a sort of cradle in which the leg lies, and is held by suitable straps l. The plates may be substantially straight from top to lower end but preferably are curved into approximate conformation to the braced leg.

Secured rigidly on the upper end of the plate 3 by rivets 8 is a head 9, formed by folding a plate of suitable gauge and shape upon itself to give a U-shape in cross section, and parallel spaced sides or leaves 12 'as shown. Pivotally mounted between the leaves by the pivot pin 13 is the lower end Id of the upper side plate 2.

The proportion and arrangement of parts is such that the edge iii of the upper side plate 2 engages the lug formed by th end ll of the head at the base of the U, when the leg portions are straight; that is, when the side plates are at one end of their respective pivotal movements as shown in Figure 3. Thus a knuckle joint of great strength is provided, the lug end I! of the head extending up vertically above the pivot pin 53 as shown, to give ample leverage as shown in Figure 1.

Means are also provided for locking the joint in the straight or unbent position. Pivoted by a pin I8 on the side plate 2, closely adjacent the upper edges of the head leaves I2 is a latch yoke 21 shown separately in Figure 4. The yoke arms enclose the plate and are extended out in front in the central eye arm 22. One of the yoke arm is extended rearwardly in the curved extension 23. With joint locks on each side of the brace, two such latch yokes are used, one for each side, the curved arms extending toward each other and being connected by a bolt 24 through the ends so that the two latches are manipulated as one.

A spring 26 is interposed between the latch and the side plate to press the latch at all times toward its locking position,- in which the yoke drops over the entire lug end of the head, and locks the upper and lower side plates rigidly together in stiff knee position.

The lower ends of the lower side plates are pivotally connected to the usual stirrup 28 in which the foot of the brace wearer rests.

The knee lock is released by pulling up either of the yoke arms 22, or pushing down anywhere on the connected arms 23. With a pivotal swinging of the lower leg, the continuou lower edge of the latch and eye arm ride on the upper edge of the lug end ll, until the leg straightens out at the end of its pivotal movement in one direction, whereupon the yoke drop over the lug endand locks the parts against pivotal movement in the other direction. Figure 3 shows the parts so locked.

plates against pivotal movement.

The wearer of a leg brace embodying the knee joint just explained can walk with a stiff knee, releasing the latch when sitting down. With very limited practice, he may learn to walk with greater ease by releasing the latch at the proper time, by a cord tied through the eye; and then allowing the swing of his braced leg to bring the mechanism to locking position before the weight is again put on the leg.

I claim: v A 1. An artificial knee joint comprising a pair of pivotally connected side plates, a stop lug fixed on one of the plates to be engaged by the other plate at the end of pivotal movement in one direction, and a spring-pressed latch on said 15 other plate for engaging the stop lug to lockthe plates against pivotal movement in. the opposite direction.

2. An artificial knee joint comprising upper and lower side plates, a head fixed on the lower 20 plate and comprising pivot plates integrally connected on one side and spaced one on each side of the upper side plate, a pivot pin through the pivot plates and the upper side plate,- and a spring pressed latch on the upper sid plate or engaging the pivot plates to lock the side plates against pivotal movement,

3. An artificial kiiee joint comprising upper and lower side plates, a U-shaped head in one engaging the 'u sh'aped head to maintain the yoke in inactive position during pivotal movement of the side plates, and a spring pressing the yoke against the U-shaped head.

5. An artificial knee joint comprising upper and lower side plates, a U-shaped head in one end of which the lower side plate is rigidly secured and in the other end of which the upper .side'plate is pivoted to lie against the base of the U at one end of its pivotal movement, a

' spring pressed latch on the upper side plate for engaging the base of the U to lock the side plates against pivotal'movement, and an extension arm on the latch for coordinating the latch with a twin structure.

RAYMOND F. MARKKULA.

REFERENCES CITED The following references are of record in the end of which the lower sideplate is rigidly se-' 30 file of this" patent:

cured and in the other end of which the upper side plate is pivoted to lie against the base of the U at one end of its pivotal movement, and a spring pressed latch on the upper side plate for engaging the base of the U to lock the side 35 1,226,160

UNITED STATES PATENTS Number Name Date 649,237 Dyson May 8, 1900 Allis May 15, 1917 

